From 92f0d4f695198fcb935cf0360f93a15bf0a6af1e Mon Sep 17 00:00:00 2001 From: Kevin Hilman Date: Mon, 16 Sep 2013 15:43:48 -0700 Subject: [PATCH 3/3] sched/nohz: add debugfs control over sched_tick_max_deferment Allow debugfs override of sched_tick_max_deferment in order to ease finding/fixing the remaining issues with full nohz. The value to be written is in jiffies, and -1 means the max deferment is disabled (scheduler_tick_max_deferment() returns KTIME_MAX.) Cc: Frederic Weisbecker Signed-off-by: Kevin Hilman --- kernel/sched/core.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e8b3350..59c7367 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2753,6 +2753,8 @@ void scheduler_tick(void) } #ifdef CONFIG_NO_HZ_FULL +static u32 sched_tick_max_deferment = HZ; + /** * scheduler_tick_max_deferment * @@ -2769,13 +2771,25 @@ u64 scheduler_tick_max_deferment(void) struct rq *rq = this_rq(); unsigned long next, now = ACCESS_ONCE(jiffies); - next = rq->last_sched_tick + HZ; + if (sched_tick_max_deferment == -1) + return KTIME_MAX; + + next = rq->last_sched_tick + sched_tick_max_deferment; if (time_before_eq(next, now)) return 0; return jiffies_to_usecs(next - now) * NSEC_PER_USEC; } + +static __init int sched_nohz_full_init_debug(void) +{ + debugfs_create_u32("sched_tick_max_deferment", 0644, NULL, + &sched_tick_max_deferment); + + return 0; +} +late_initcall(sched_nohz_full_init_debug); #endif notrace unsigned long get_parent_ip(unsigned long addr) -- 1.7.10.4